Researchers from Yale University and Harvard University have shown that they can use morpholinos to protect a microRNA target gene from suppression in order to evaluate specific miRNA-mRNA interactions in zebrafish.
“Thousands of miRNA-mRNA interactions have been predicted, but less than a dozen have been shown to have an in vivo function,” according to the researchers, whose study appeared in Science. “The sequence selectivity of … target protectors makes them excellent agents to disrupt specific miRNA-mRNA interactions.”
These oligos “not only uncover the physiological role of miRNA-mRNA interactions but also illustrate how miRNA phenotypes are a composite created by up-regulation of multiple targets,” they add.
In the Science paper, the investigators used morpholinos complementary to miRNA binding sites in target mRNAs, hypothesizing that the overlap might interfere with miRNA-mRNA interactions and protect the target mRNA from the miRNA.
They achieved specificity using morpholino sequences specific to the 3’ UTR of target mRNAs.
“Basically, the most important feature of these oligos is that in the absence of the microRNA [they] shouldn’t do anything to the mRNA,” says Antonio Giraldez, an assistant professor of genetics at Yale and co-author of the Science paper. “You don’t obtain an artificial gain of function because [the target protector] binds to and stabilizes the mRNA independently of the presence or absence of a functional microRNA in that cell.”
While Giraldez sees great potential for the target protector technology in basic research, he noted that the approach, if combined with other kinds of oligos, might also be used therapeutically.
“In principle, any other … stable oligo that binds specifically to RNA should be able to inhibit microRNA activity,” he says. “I could imagine that 2’ O-methyl oligos or antagomirs, which are usually used to bind a microRNA, might be used to bind the mRNA.”
— Doug Macron
Short Reads
Quark Pharmaceuticals and the State University of New York at Buffalo’s Center for Hearing and Deafness extended their research agreement. SUNY Buffalo is conducting preclinical studies of Quark’s siRNA-based hearing loss drug candidate AHLi-11, which targets p53 and may treat problems associated with trauma or otoxic drugs.
Opoko Health began its phase III trial of bevasiranib, a siRNA-based drug for wet age-related macular degeneration. This international study will help determine if bevasiranib is as safe and effective as Genentech’s Lucentis in preventing vision loss. Opko acquired bevasiranib when it merged with Acuity Pharmaceuticals.
The University of Massachusetts Medical School received an Australian patent for its siRNA molecules and the methods to use them in in vivo mammalian cells. A portion of what is covered by this patent is licensed by RXi Pharmaceuticals. RXi has exclusive rights to the technology for inhibiting human cytomegalovirus, familial amyotrophic lateral sclerosis’s mutant SOD1 gene, and gene targets associated with type 2 diabetes and obesity.
The Samuel Waxman Cancer Research Foundation awarded money to five research teams, including one at Johns Hopkins Kimmel Cancer Center that focuses on microRNA research. The project that received the funding will be researching the role of miRNAs in acute leukemia.
Patents
US application 20070207974. Functional and hyperfunctional siRNA. Inventors: Anastasia Khvorova, Angela Reynolds, Devin Leake, William Marshall, and Stephen Scaringe. Filed: March 30, 2005.
The patent says that siRNA technology can be use to silence specific genes if efficient sequence selection is used. “By selecting particular siRNAs by rationale design, one can maximize the generation of an effective gene silencing reagent, as well as methods for silencing genes,” says the application abstract.
US application 20070185049. RNA interference mediated inhibition of histone deacetylase (HDAC) gene expression using short interfering nucleic acid (siNA). Vasant Jadhav and Joseph Carroll. Filed: November 2, 2006.
This patent application describes compounds, compositions, and methods to study how to treat diseases and conditions stemming from changes in histone deacetylase gene expression and activity. In particular, the patent abstract mentions short interfering nucleic acid, short interfering RNA, double-stranded RNA, microRNA, and short hairpin RNA that can mediate RNA interference of HDAC gene expression.
Data Point
$6.2 million
CytRx’s second-quarter net loss reached $6.2 million, up from $5.5 million in the year-ago period.